An exemplary reservoir was simulated in the Eastern Alps, located between
Watzmann and Berchtesgaden at approx. 1200 m altitude (see figure), in order
to assess the influence caused by the additional loads of reservoir and dam, as well
as the changes in pore pressure. Additionally, the interaction between accumulated
water and dam was investigated.
The rock mass was simulated poroelastically for this purpose, i.e. hydro-mechanically
coupled. The groundwater saturated zone is located approx. 100 m below surface. The
dam is approx. 175 m high, the reservoir depth is max. 150 m. The total volume of the
reservoir is 53 million m3. Storing water in the reservoir leads to water percolating
into the unsaturated zone, which in turn leads to reduced effective stresses. Significant stress changes (± 2 MPa)
radiate down to a depth of 500 m and are not congruent with the superposition of the
pore pressure (smaller than 1.5 MPa). Zones of reduced effective stresses can lead to reactivation
of critically stressed discontinuities and induce seismicity. Additionally, the simulation can be used to evaluate the
interaction between the damed water and the dam itself.
outcome
- determination of stress tensor
- determination of pore pressure